Japanese Patent Provisional Publications No. 61(1986)-275742 and No. 61(1986)-278849 (the contents of these two publications are described in U.S. Pat. No. 4,912,011 and European Patent Provisional Publication No. 0203613A) disclose a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains silver halide, a reducing agent, a polymerizable compound and a color image forming substance. The silver halide, the reducing agent, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer.
An image forming method using the light-sensitive material comprises the steps of imagewise exposing to light the light-sensitive material to form a latent image of the silver halide, heating the light-sensitive material to polymerize the polymerizable compound within the area where the latent image has been formed, pressing the light-sensitive material on an image-receiving material to transfer the unpolymerized polymerizable compound with a color image forming substance to the image-receiving material, so as to form an image on the image-receiving material.
Further, a method of polymerizing the polymerizable compound within the area where the latent image of the silver halide has not been formed is disclosed in Japanese Patent Provisional Publications No. 61(1986)-243449, No. 61(1986)-260241 (the contents of these two publications are described in European Patent Provisional Publication No. 0202490A), No. 2(1990) 141756 and No. 2(1990)-141757.
The development and polymerization reactions in the image forming method smoothly proceed in alkaline conditions. Therefore, the light-sensitive layer of the light sensitive material preferably contains a base precursor as an image formation accelerator. Various base precursors have been known, as is described in Japanese Patent Provisional Publication No. 62(1987)-264041 (corresponding to U.S. Pat. No. 4,792,514 and European Patent Provisional Publication No. 0203613A).
In order to accelerate the development and polymerization reactions, it is preferred to incorporate the base precursor into light-sensitive microcapsules, as is described in Japanese Patent Provisional Publications No. 64(1989)-32251 (corresponding to U S. Pat. No. 4,939,064 and European Patent Provisional Publication No. 0301539A) and No. 1(1989)-263641, and Japanese Patent Applications No. 1(1989)-182245 and No. 1(1989)-160148. The base precursor is composed of a salt of an organic base with a carboxylic acid, and is generally used in the form of solid particles.